1. Technical Field
The present invention relates to a detector for detecting leaks of a gas from a container for the gas.
2. Description of the Prior Art
U.S. Pat. No. 4,164,699 to Timoshenko et al. discloses a gas detector which has a thermistor within an electrical circuit. The thermistor is a platinum wire. The platinum functions as a catalyst for the combustion of the gas being detected. This combustion raises the temperature of the platinum wire, which changes the wire's resistance. The change in resistance is detected in the electrical circuit.
U.S. Pat. No. 4,806,314 to Fertig et al. discloses a detector suitable for detecting low concentrations of a hydrocarbon contaminant in an air stream. The detector contains a resistance element which is positioned in the air stream. The resistance element is coated with palladium. When the resistance element is electrically heated, the palladium functions as a catalyst to oxidize exothermically the hydrocarbon contaminant in the air stream. The detector has a second resistance element which is positioned in the air stream ahead of the palladium coated resistance element. The second resistance element is provided with an intermittent current. When the current to the second resistance element is on, the hydrocarbon contaminant is oxidized, and no oxidation takes place at the palladium coated element. This provides a reference noise level for the palladium coated element.
U.S. Pat. No. 4,854,155 to Poll discloses a catalytic gas detector which includes a resistance gas sensing element in a bridge circuit. A first power source is connected to terminals of the bridge circuit. The circuit has a second power source which includes a timer. The purpose of the second power source and timer is to direct a temporary current of relatively high voltage through the sensing element to burn off impurities on the surface of the sensing element.